What do "Thane of Glamis" or "Thane of Cawdor" mean in Macbeth?
*Original question has been edited down to a single question (per eNotes policy).
In Act I, scene three, the witches' wait for Banquo and Macbeth in order to make their cunning predictions concerning the two men. When Macbeth approaches, three different witches address him by three distinct titles: Thane of Glamis, Thane of Cawdor, and "Macbeth, that shalt be King hereafter!" (I.iii.52)
Of course, these are titles that represent a feudal position in King Duncan's kingdom. A 'thane' is another word for a high ranking nobleman like a Baron. Macbeth is already Thane of Glamis, but when the witches also name him as being Thane of Cawdor, Macbeth reveals his surprise at the witches' prediction:
"By Sinel's death I know I am Thane of Glamis;
But how of Cawdor? The Thane of Cawdor lives,(75)
A prosperous gentleman; and to be King
Stands not within the prospect of belief,
No more than to be Cawdor" (I.iii.74-78).
In this scene, Macbeth eagerly accepts the witches' lofty predictions, hoping that indeed they will come true.
In the first Act of the play, Macbeth is introduced to the reader as the Thane of Glamis. Historically speaking, the term "thane" relates to the Peerage of Scotland. A thane was a man who held land directly from the king, in return for loyalty and military service. Moreover, "Glamis" refers to an area of Scotland in which the thane holds his lands and exerts power.
In Scene II, it is revealed that the current Thane of Cawdor (another area of Scotland) has rebelled against the king and is killed. In the next scene, the witches prophesy that Macbeth will become the next Thane of Cawdor. This is a considerable honor for Macbeth (because it will boost his landholding, power, and prestige), so he is eager to see if the prophecy comes true.
At the end of this scene, Macbeth is indeed named the Thane of Cawdor, as a gesture of recognition by King Duncan. While he is given the title as a reward for his loyalty and military prowess, it feeds Macbeth's sense of ambition and leaves him wondering if the third prophecy, that he will rule Scotland, will come true.